Abstract:

Field investigations and artificial pollination experiments were conducted to explore the flowering characteristics and breeding system of the remnant Myricaria laxiflora (Franch.) P. Y. Zhang et Y. J. Zhang population in Dianjun Yanzhiba in Yichang, downstream of the Three Gorges Dam. Results showed that: (1) The flowering period of the M. laxiflora remnant population extended from September to April, with a peak blooming period from October to November and a single flower lifespan of two to seven days. The temporal and spatial overlap of the female and stamen structures within a single flower facilitated self-pollination. (2) The out-crossing index (OCI) was 2 and the pollen-ovule (P/O) ratio was 329, suggesting that M. laxiflora operates under a facultative autogamy (xenogamy) system. (3) Artificial pollination experiments demonstrated that while M. laxiflora exhibited partial self-compatibility, the rate of seed setting from cross-pollination significantly exceeded that of self-pollination. The study suggested that a high rate of self-crossing within the remnant population. Thus, conservation measures should be implemented to reduce human disturbance and protect the habitat and genetic diversity of the remnant populations should be subjected to ongoing surveillance.

摘要：

通过野外调查及人工授粉实验，对三峡大坝下游宜昌点军胭脂坝残存疏花水柏枝（Myricaria laxiflora (Franch.) P. Y. Zhang et Y. J. Zhang）居群开花特性及繁育系统进行观测和研究。结果显示：（1）疏花水柏枝残存居群花期较长（9月至次年4月），群体盛花期为10-11月，单花花期2~7 d，单花雌雄蕊在时间和空间上有一定重叠，有利于自花授粉；（2）杂交指数（OCI）为2，花粉胚珠比（P/O）为329，均显示疏花水柏枝为兼性自交（异交）系统；（3）人工控制授粉实验结果表明，疏花水柏枝具有部分自交亲和性，但异交处理的结实率显著高于自交处理。推测该残存居群存在自交成分偏高的现象，保护措施应以减少人为干扰和保护生境为主，并加强对残存居群遗传多样性水平的监测。